Many electronic integrated circuits are formed by a strategic placement and interconnection of selected electronic devices, such as transistors and the like, within a semiconductor substrate. The electronic devices are interconnected using an array of surface conductors carrying data signals through which the devices communicate. The electronic devices, however, must be sufficiently isolated from one another so that the signals in each respective electronic device do not interfere with and degrade the others' signal quality.
Device isolation is typically achieved using local oxidation of silicon ("LOCOS") or shallow trench isolation ("STI"). In these device isolation techniques, isolation is commonly provided by forming a recess or trench between two active areas, upon which the electronic devices are located, and filling the trench with an isolation material. In either shallow trench isolation processes or local oxidation of silicon isolation techniques, the isolation for devices is typically spaced at O.5 .mu.m or greater and a physical delta-.omega. (difference between the drawn active area width and actual active area width) of 0.30 .mu.m or greater.
There is a need in the industry for a technique to allow fabrication of channel devices with denser packing, and thus separated by narrower isolation regions. The present inventive process provides a means to form device isolation trenches separated by about 0.10 .mu.m to about 0.35 .mu.m, about one-half the distance available with current technology. Further, the process yields a small physical delta-.omega. of less than about 0.1 .mu.m. This process is a modification of conventional processing and does not require advanced photolithography or plasma etch equipment. Thus, there is a significant cost benefit to employing the inventive technology, since other techniques to achieve similar results would require extensive and costly capital improvement. The present inventive process takes advantage of the characteristics of micro-trenching by incorporating them into isolation trenches. When the present inventive process is used in conjunction with standard techniques, such as STI, a device can be fabricated with variable trench width and variable distances between the trenches.